Drug toxicity often goes undetected until clinical trials, the most costly and dangerous phase of drug development. Both the cultures of human cells and animal studies have limitations that cannot be overcome by incremental improvements in the drug testing protocols. A new generation of preclinical models - in form of integrated human tissue platforms, would be transformative to drug screening and predictive modeling of disease. This multiphase (UH2/UH3) proposal integrates in a novel and synergistic way some recent breakthroughs from four leading laboratories, towards developing a vascular/liver/cardiac microtissue system predictive of integrated human physiology. In the UH2 phase, we aim to establish iPS-based vascular, liver and cardiac microtissues providing (i) hierarchical tissue-specific architectures, (ii) functional representation of human biology of health, injury and disease, (iii) real-time biological readouts, and (iv) compatibility with high-throughput/high-content multi-tissue platforms for studies of drug toxicity and over long periods of time (e4 weeks). The work will be done using iPS-derived cells (to provide a large diversity of normal and disease genotypes) and using nondestructive monitoring of the tissue architecture and function (to provide real-time insights into the progression of cell and tissue responses). Our overall hypothesis is that tissue specific structure-function relationship can be achieved through control and biomimetic application of microenvironemental cues in vitro. Such microtissues will then be high-fidelity models for drug testing and toxicology. In the UH3 phase we aim to deploy an integrated cardiac/hepatic/vascular platform and demonstrate its utility for a broad range of genotypes and drugs. Towards these goals, we will pursue a set of coordinated aims with constant feedback, evaluation, and monitoring of the milestones. Aim 1 is to develop cell-type specific labeling and sensing systems for on-line assessment of tissue architecture and cell function. Aim 2 is to develop a perfusable branching vascular network serving as a model of the vascular bed and for assembling vascularized liver and cardiac tissues. Aim 3 is to develop a liver module by assembling hepatic microtissues in hydrogel around the vascular tree. Aim 4 is to develop a cardiac module by assembling matured cardiac microtissues in hydrogel around the vascular tree. Aim 5 is to conduct studies of disease susceptibility, for the individual tissue modules and in the multi-tissue platform. Aim 6 is to investigate human physiology and disease in multi-tissue platforms. This way, we aim to develop a radically new technology for studies of drugs in human tissue models. If successful, the proposed approach would radically enhance the translation of drug discovery into human applications, by enabling accurate preclinical data for better, faster and cheaper clinical trials.